Aims To assess and compare the incidence of cardiovascular (CV) events, by CV phenotype, between patients with ankylosing spondylitis (AS), rheumatoid arthritis (RA) and the general population.

Methods Using linkages of national and population-based registers, we identified one cohort of prevalent patients with AS (n=5358), one with RA (n=37 245) and one with matched general population subjects (n=25 006). These cohorts were identified in 2006 through 2011 and were followed in 31 December 2012, for first ever occurrence of acute coronary syndromes (ACS), deep venous thromboembolism, pulmonary embolism and stroke, respectively. For each outcome, we calculated incidence rates standardised to the age and sex distribution of the AS cohort, as well as relative risks using Cox proportional hazards models.

Results Based on 69 ACS events during 20 251 person-years of follow-up of the patients with AS, and 966 events during 127 014 person-years in the RA cohort, the age/sex-adjusted relative risks for ACS compared with the general population was 1.3 (95% CI 1.0 to 1.7) for AS and 1.7 (1.4 to 2.0) for RA. For thromboembolic events, the corresponding risks were 1.4 (1.1 to 1.9) in AS and 1.8 (1.5 to 2.1) in RA. Finally, for stroke, the relative risks were 1.5 (1.1 to 2.0) in AS and 1.5 (1.2 to 1.8) in RA, compared with the general population.

Conclusions Prevalent patients with AS are at a 30%–50% increased risk of incident CV events. When compared with patients with RA, this level of increase was similar for stroke, but only half as high for ACS and thrombotic events.